VESA (Video Electronics Standard Association) developed a new display interface compression standard for mobile or smartphone displays or hand-held devices called VESA Display Compression-Mobile or VDC-M. VDC-M targets higher compression ratio than Display Stream Compression (DSC) while maintaining visually lossless quality as of DSC at the cost of increased complexity. VDC-M has application in mobile devices that use a display link, such as the MIPI display serial interface (DSI).
In particular, the VDC-M compression standard is fixed rate codec (encoder-decoder) and supports compression rates down to 6 bits/pixel for a RGB 4:4:4 signal source with 8 bits per color component. VDC-M is a block based codec with a block size of 8×2 pixels. In operation, the VDC-M codec operates by applying or testing multiple coding modes for each block and selecting a best coding mode for a block based on a rate-distortion cost. A different coding mode may be selected for each block. With the selected coding mode, the data samples are encoded using an entropy encoder to generate a compressed bitstream. Substream multiplexing is implemented to enable parallel parsing of the compressed bitstream to achieve a high decoder throughput.